Deck Door Replacement — Threshold to the Decking, Flashed to Ledger
The door onto the deck is where the house and the deck meet, and that joint is where water gets in.
Reply within one business day. Or call / text 763-204-2099.
A deck door replacement is a new prehung slider, French or entry door onto a deck, with two details a plain swap skips: the threshold set above the deck boards so meltwater drains away, and the flashing lapped over the deck ledger so the rim joist stays dry. JMB Builders supplies and installs them across the Twin Cities metro. Priced per door, quoted from photos, reply within one business day.
- Priced per door, door supplied
- Slider, French or hinged door onto the deck
- Threshold height and ledger flashing checked
Every deck door has a problem the front door does not: a deck bolted to the wall right under it. The deck ledger sits against the rim joist, the deck boards run up to the threshold, and snow sits on the deck against the bottom of the door all winter. If the deck boards are at or above the threshold, meltwater runs toward the house instead of away. If the ledger was never flashed, or the flashing stops short of the door, water gets behind the ledger and into the rim and the subfloor under the door. The soft floor just inside a deck door is one of the most common things we find when an old patio door comes out.
So a deck door replacement is two jobs. The door itself is a prehung slider, hinged French pair or single entry door, from options such as Andersen, Pella, ProVia, JELD-WEN or Therma-Tru, chosen for the room and the exposure the way any patio door is. The joint is the second job. Once the old door is out we look at the rim behind the ledger and the subfloor under the sill, set the new frame on a sill pan, and lap the flashing tape from the housewrap down over the top of the ledger flashing so water that reaches the wall ends up outside the ledger. Where the deck boards are too high against the sill, the first board is cut back or lowered so the threshold sits above the decking with a gap for water to drop through.
A deck also moves. Posts on shallow footings heave with frost and settle in spring, and a deck that lifts against the threshold in February will push on the new door. We check how the deck is attached and whether it has moved against the old sill, and we set the door so a little deck movement does not bind it. Painting of the trim is quoted as a separate line — or leave it primed and caulked and paint it yourself.
Get a written quote for this job
Three photos and a sentence is enough: a reply within one business day, or ask for a free in-home estimate. Or text the photos to 763-204-2099.
What you supply
- Photos of the door from the deck showing the deck boards meeting the threshold, and from inside
- A photo of the ledger from under the deck if you can get one, or tell us the deck is on grade
- Slider, French or single entry door, and the frame material and color
- Whether the floor inside the door feels soft or the threshold has sunk
- Hardware finish, or the handle set you bought
What JMB supplies
- Measurement of the opening and the order for a prehung slider, French pair or entry door
- Removal and haul-away of the old door, frame and trim
- Check of the subfloor, rim joist and the area behind the ledger once the old door is out, quoted from the photos
- Sill pan under the new threshold, flashing tape lapped from the housewrap over the ledger flashing, foam and sealant
- Cutting back or lowering the first deck board where the decking is too high against the threshold
- A check of how the deck is attached and whether frost movement has pushed on the old sill
- Interior casing and exterior trim fitted to the siding and the deck
- Handle set and lock installed, from the door order or the set you bought
- Painting of the trim, quoted as its own line
- Photos of the finished door in your job folder
How it is priced: per door
Quoted in writing from your photos, with a reply within one business day. What moves the number:
- Slider vs. French pair vs. single entry door
- Frame material and glass package
- Soft subfloor or rim joist behind the ledger, found once the old door is out
- Deck boards cut back or lowered at the threshold
- Ledger flashing missing or stopping short of the door, and what it takes to lap it right
- A deck that has heaved against the sill
- Painting of the trim, quoted as a separate line
Send a photo from the deck looking down at where the boards meet the threshold, and one from under the deck at the ledger if you can. Those two photos tell us most of the job.
How long it takes
One deck door in a sound opening: most of a day on site. Add a few hours for rim or subfloor work behind the ledger or for trimming the decking. The door is ordered after you approve the quote.
How your project works
- 1
Send photos, get a written quote
Send three photos of the space and a sentence about what you want. You get a clear, itemized reply within one business day. Prefer a look in person? A free in-home estimate is always an option.
- 2
Pick materials, or bring your own
We help you choose profiles and materials that fit the house and the budget, or match your existing millwork exactly — or you buy the door or trim yourself and we install it. Everything is confirmed before the crew is scheduled.
- 3
Clean, precise installation
The crew shows up on time, protects floors and furniture, and installs with tight joints and consistent reveals. Photos of the finished work go in your job folder.
- 4
Walkthrough and invoice
We walk the finished work with you. If anything is not right, we fix it before we call the job done. Then one invoice, paid by check or direct deposit — no card fees, no payment links.
Situations and options
Slider onto the deck
A two- or three-panel slider in vinyl, fiberglass or clad, with the threshold set above the deck boards and a sill pan under it. The most common deck door and the easiest to seal.
Hinged French door, outswing onto the deck
A pair swinging out keeps the floor inside clear, but snow on the deck can hold it shut and the sill needs an outswing threshold. Best under a covered deck or where the deck is kept shoveled.
Single entry door to the deck
A steel or fiberglass half-lite door for a narrow opening onto a small deck or landing, often off a bedroom or a lower level. Same sill pan and ledger detail as the big doors.
Door with decking lowered at the sill
Any of the above plus cutting back or dropping the first deck board so the threshold sits above the decking with a gap for water to drop through. Done the same day.
Deck Door Replacement — Threshold to the Decking, Flashed to Ledger: questions, answered
How high should the deck be below the patio door threshold?
The deck boards should sit below the threshold so water and melting snow drain away from the door, not toward it, with a gap at the wall for water to drop through. When the deck was built flush with or above the sill, we cut back or lower the first board as part of the door replacement. A threshold buried in the decking is the usual reason the floor inside is soft.
Why is the floor soft inside my deck door?
Water got under the old threshold, from snow sitting on the deck against the door or from deck boards that drain toward the house, and with no sill pan it went into the subfloor and the rim joist behind the deck ledger. Once the old door is out we see how far it went and deal with it while the opening is open, then set the new door on a sill pan that drains out.
Does the deck ledger flashing get redone when the door is replaced?
At the door, yes. The flashing tape from the housewrap is lapped down over the top of the ledger flashing so water that runs down the wall ends up outside the ledger. If the ledger has no flashing or it stops short of the door, we tell you what we see and quote what it takes to fix it at the opening; reflashing the whole ledger is a deck job and is quoted separately.
Can a deck that heaves in winter damage the new door?
It can push on the sill if the deck is tight against the threshold and the posts are on shallow footings. We check whether the deck has moved against the old door, leave a gap at the threshold, and set the new frame so a little deck movement does not bind it. A deck that moves a lot every winter has a footing problem that a door cannot fix.
Slider or French door onto the deck?
A slider when snow sits on the deck, because nothing has to swing over it, and when the room is tight. An outswing French door when the deck is covered or kept clear and you want the floor inside open. An inswing French door when the room has the space. The sill and flashing detail is the same for all three.
Do you replace a door onto a deck that is being rebuilt?
Yes, and that is the best time. With the old deck off, the ledger and rim are open, the flashing can be lapped right, and the new deck is framed so the boards land below the threshold. Tell us the timing and we schedule the door for the window between the old deck coming off and the new boards going down.
Recent JMB work, from our job log
59 installs recorded across 30 Twin Cities communities since Dec 2025. Window and door installs for homeowners and the builders we work with. Counts come straight from our job log; no customer names.
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Read morePage reviewed October 10, 2026 · JMB Builders LLC, MN license BC809005 · All doors pages
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Door Replacement & Installation near you
Based in Zimmerman, scheduling across the Twin Cities metro. Closest first: